Contents-distributing system and contents-distributing method

ABSTRACT

The utilization of various distributed contents is restricted by a simple method, its restriction can be released, and an accurate collection of fees for the contents is made possible. A client terminal  30  sends a request of contents (musical scores) and a key file to a server  10  via a communication line  20.  In response to the request of these, a WEB server  11  transmits the contents stored in a database  13,  and a key issuing server  12  transmits the key file. The WEB server  11  charges a fee when the key file is requested. A viewer  32  can only display the musical scores in the absence of the key file. With the use of the key file, however, the viewer  32  can print the musical scores as well. The key file is formed in accordance with a random value that is synchronized with the timing of an instruction for purchasing the contents.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a contents-distributing systemfor distributing musical scores, sentences, various figures, music data,programs, and others from a server to a client terminal to make thecontents utilizable by the client terminal. Further, the presentinvention also relates to a contents-distributing method which isrelated to the contents-distributing system, a server and a clientterminal utilized in the contents-distributing system, and acomputer-readable recording medium containing a program applied thereto.

[0003] 2. Description of the Prior Art

[0004] From the past, it is well-known in the art to obtain variouscontents such as musical scores, sentences, various figures, music data,programs, and others from a server via a communication line such as theinternet or an exclusive-use line using a personal computer. In thiscase, there are cases in which various contents can be obtained free ofcharge, and cases in which they are obtained at a charge.

[0005] However, even in the above-mentioned conventional case ofallowing various contents to be available at a charge, after a user hasonce downloaded the contents into a personal computer or the like, theuser can utilize the downloaded contents freely, whereby the user cancopy the contents without limitation simply by paying the charge once.For this reason, the server side hesitates to distribute all thecontents to users, thereby imposing an obstacle against freedistribution of various contents.

SUMMARY OF THE INVENTION

[0006] The present invention has been made in order to solve theaforementioned problems of the prior art, and an object thereof is toprovide a contents-distributing system in which the utilization ofvarious distributed contents is restricted by a simple method, itsrestriction can be released, and an accurate collection of fees for thecontents is made possible. Another object of the present invention is toprovide a contents-distributing method which is related to thecontents-distributing system, a server and a client terminal utilized inthe contents-distributing system, and a computer-readable recordingmedium containing a program applied thereto.

[0007] In order to achieve the aforementioned objects, thecharacteristic feature of the present invention lies in that, in acontents-distributing system in which one or more contents aredistributed from a server that stores a plurality of contents in adatabase to a client terminal or which includes a client terminal thatstores a plurality of contents in advance, a key file for releasing therestriction on utilization of one or more contents is supplied from theserver to the client terminal in response to a request sent from theclient terminal to the server, whereby the restriction on theutilization of the aforesaid one or more contents is released in theclient terminal on the basis of the supplied key file.

[0008] In this case, the restriction on the utilization is, for example,to introduce the contents to a user of the contents by utilization ofonly a part of the contents, and more specifically described, it is toprohibit the musical scores, i.e. the contents, from being printed(display or the like is permitted). By the key file supplied from theserver to the client terminal, the restriction on the utilization of thecontents is released in the client terminal. As a result of this, by thepresence of the key file, free utilization of the contents is restrictedeven if the user of the contents has obtained only the contents, so thatthe server side can freely supply the contents to the client terminal ina form such as communication or a recording medium. Further, since thekey file is provided independent from the contents, the restriction onthe utilization such as copying of the contents can be easily added to aperson that has obtained the key file, as described below.

[0009] For example, as the release of restriction on the utilization ofthe contents by a key file, release of the restriction on theutilization of the contents under constraint of the number of times forthe utilization or under constraint of time, or erasure of the key fileutilized for the release of the restriction on the utilization of thecontents after the release of the restriction on the utilization, isadopted. By this, unlimited utilization of the contents can be easilyinhibited.

[0010] Further, if a fee is charged on the user in the client terminalat the time of request for the key file, the fee can be easily chargedon the user.

[0011] Further, another characteristic feature of the present inventionlies in that it is possible to allow reissuance of the key file for apredetermined number of times or within a predetermined period of timeafter the key file is initially transmitted, in accordance with therequest of the key file from the client terminal. By this, the user thathas lost the key file by error can be allowed to utilize the contents.

[0012] Further, in preparation, supplying, and utilization of the keyfile, an identification data specific to a timing of the request of thekey file is generated and stored when the client terminal sends therequest of the key file to the server, and the identification data issupplied to the server together with the request of the key file. Theserver supplies the key file containing the identification data to theclient terminal, and the client terminal releases the restriction on theutilization of the contents by comparison between the identificationdata stored in the client terminal and the identification data containedin the transmitted key file. In this case, the identification data maybe set, for example, at a value which changes at random in accordancewith passage of time and which is synchronized with the timing of therequest of the key file.

[0013] By this, the identification data is not set at a substantiallyidentical value, and can be easily formed, so that the safety in therelease of the restriction on the utilization of the contents can beeasily ensured. In addition, if this key file is encoded, the safety inthe release of the restriction on the utilization of the contents can bemaintained at a further high level.

[0014] Further, another characteristic feature of the present inventionlies in a contents-distributing method, a server and a client terminalutilized in the contents-distributing system, and a computer-readablerecording medium containing a program applied thereto, for realizing thedistribution of contents as described above. By these, the afore saidcontents-distributing system can be appropriately constructed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a block diagram illustrating a contents-distributingsystem as a whole according to one embodiment of the present invention;

[0016]FIG. 2 is a functional diagram illustrating a work flow accordingto the distributing system of FIG. 1;

[0017]FIG. 3 is a flow chart of a key input processing program showingthe utilization of contents by a client terminal;

[0018]FIG. 4 is a detailed flow chart of a file processing routine ofFIG. 3; and

[0019]FIG. 5 is a detailed flow chart of a printing processing routineof FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereafter, one embodiment of the present invention will bedescribed. In this embodiment, the contents-distributing systemaccording to the present invention is applied to a musical scoredistributing system for distributing musical scores to a user forutilization. Referring to FIG. 1, this musical score distributing systemincludes a computer 10 for distribution (referred to as a server in thisspecification), a communication line (network) 20 such as the internet,a public telephone line, an exclusive-use line, or a LAN, and aplurality of computers for receiving the distribution (referred to asclient terminals in this specification) as terminal devices. Here, inFIG. 1, only one client terminal 30 is shown.

[0021] The server 10 includes a WEB server 11, a key-issuing server 12,a database 13, and a communicating part 14.

[0022] Actually, in this case, the WEB server ll and the key-issuingserver 12 are programs that are stored in a program memory in the server10. In response to a signal from the client terminal 30, the WEB server11 supplies various data including the contents file stored in thedatabase 13 and the key file issued by the key-issuing server 12 as wellas programs and others to the client terminal 30 via the communicatingpart 14 and the communication line 20 according to a given communicationprotocol (for example, an HTTP (Hyper Text Transfer Protocol)). The WEBserver 11 also receives various data and programs from the clientterminal 30 via the communication line 20 and the communicating part 14.The contents file contains contents data and a contents identificationdata CID corresponding to the contents data.

[0023] The key-issuing server 12 prepares an encoded key file on thebasis of the contents identification data CID that designates each ofthe contents in correspondence with each of the contents and a runtimeidentification data RID supplied from the client terminal 30. Here, theruntime identification data RID is a specific data issued according tothe timing of an instruction for purchase when the client terminal 30purchases the contents file, and the RID is utilized for confirmation ofthe purchase.

[0024] The database 13 is a large-capacity memory device such as a harddisk or an CD that stores a large number of encoded contents filesrepresenting a large number of musical scores. Here, the contents inthis case refer to musical scores, and the contents file is made of thecontents data, the contents identification data CID, and others. Thecontents data are musical score data made of a large number of datarepresenting a series of musical notes, musical symbols, and others forprinting the musical scores. The contents identification data CID is aspecific data representing the contents data (musical score data) foridentifying the contents data. Further, the musical score data may beconstructed with image data obtained by capturing the musical scoresimply as a figure. The communicating part 14 transmits and receivesvarious data and programs to and from the communication line 20according to a given communication protocol (for example, an HTTP).

[0025] The client terminal 30 includes a WEB browser 31, a viewer 32, aruntime ID generating part 33, a data memory 34, and a communicatingpart 35.

[0026] Actually, in this case, the WEB browser 31, the viewer 32, andthe runtime ID generating part 33 are programs stored in a programmemory in the client terminal 30. The WEB browser 31 reads various datasuch as a contents file and a key file as well as programs for storagethereof in the data memory 34 in accordance with a supplied instruction,gives an instruction to the viewer 32, and supplies various data andprograms to the server 10 via the communicating part 35.

[0027] The viewer 32 functions as a helper application of the WEBbrowser 31, and reads the contents file, the key file, and others storedin the data memory 34 to let the contents file utilizable by the user inaccordance with an instruction of the user. This viewer 32 includes acontents file reading part 32 a and a key file reading part 32 b. Thecontents file reading part 32 a deciphers the contents files stored inthe data memory 34 to decode the contents data and the contentsidentification data CID corresponding to the contents data. The key filereading part 32 b deciphers the key file stored in the data memory 34 torestore the contents identification data CID and the runtimeidentification data RID. The viewer body part 32 c cooperates with theWEB browser 31 to send and receive data to and from the server 10 andcooperates with the contents file reading part 32 a and the key filereading part 32 b to let the contents file utilizable by the user.

[0028] The runtime ID generating part 33, in response to an instructionof the user, generates a runtime identification data RID specific to thetiming of the instruction. For example, the runtime ID generating part33 incorporates a random number generator that generates a random numberof plural bits in accordance with passage of time, and generates therandom number as a run time identification data RID in synchronizationwith the instruction timing of the user.

[0029] The data memory 34 is a memory device having a comparativelylarge capacity such as a hard disk or an CD that stores the contentsfiles, the key files, and others. The communicating part 35 correspondsto the communicating part 14 of the server 10, and transmits andreceives various data and programs to and from the communication line 20in accordance with a give communication protocol (for example, an HTTP).

[0030] The client terminal 30 also includes an input key 36, a display37, a printer 38, and a driver 39. The input key 36 includes keyscorresponding to characters or numerals, a mouse and others to supply aninstruction signal, an input data, and others corresponding to a keyoperation of the user to the WEB browser 31, the viewer body part 32 c,and the runtime ID generating part 33. The display 37 visually displayscharacters and figures, and displays various ones including a musicalscore in accordance with an instruction from the WEB browser 31, theviewer body part 32 c, or the like. The printer 38 prints the charactersand figures, and prints various ones including a musical score inaccordance with an instruction from the WEB browser 31, the viewer bodypart 32 c, or the like. The driver 39 is controlled by the WEB browser31, the viewer body part 32 c, and other programs (not illustrated) toread data and programs from an external recording medium such as a CD(Compact Disk), an MD (Mini Disk (trademark)), or a flexible disk, andto write data and programs to the recording medium.

[0031] Next, an operation of the contents-distributing systemconstructed as above will be described; however, before that, aconstruction of the distributing system will be described. On the server10 side, a program memory of a computer having a comparatively largesize is allowed to store a general program for realizing the WEB server11 and an exclusive-use program for realizing the key-issuing server 12.In allowing these programs to be stored in the program memory, theprograms prepared in advance and stored in a CD, an MD, or the like maybe allowed to be stored in the program memory of the server 10 with theuse of a driver (not illustrated). Further, a lot of contents files eachmade of the contents data representing the musical score and thecontents identification data CID corresponding to the contents data areprepared, and the prepared contents files are stored in the database 13.For facility in searching for each musical score (music), the contentsfiles are allowed to contain the genre of the music, the difficulty ofplaying the music, the price in selling the music, and others inaddition to the name of the music and the composer of the music.Further, addition and renewal can be made at all times on the contentsfiles in the database 13.

[0032] On the other hand, on the client terminal 30 side, a programmemory of a general personal computer is allowed to store a generalprogram for realizing the WEB browser 31 and an exclusive-use programfor realizing the viewer 32 and the runtime ID generating part 33. Inthis case, these programs may be downloaded from the server 10 oranother computer by a program (not illustrated). Further, a CD, an MD,or the like that stores the aforesaid programs may be distributed to theuser in accordance with a request of the user, for installation by theuser via the driver 39 with the use of a program (not illustrated).

[0033] Next, an operation of the contents-distributing systemconstructed as above will be described along the procedure shown in FIG.2. First, the user starts the WEB browser 31 of the client terminal 30and sends a request of a contents file to the WEB server 11 with the useof the input key 36 (S100). In this case, by accessing the server 10,the user lets the display 37 display the menu data and others suppliedfrom the server 10 and requests for a musical score of a desired musicby searching for the musical score with the use of the input key 36(S102).

[0034] In response to these, the WEB server 11 of the server 10 readsthe requested contents file out from the database 13 (S104), andtransmits a part of the contents file to the WEB browser 31 of theclient terminal 30 (S106). However, the part of the contents filecontains the contents identification data CID corresponding to thecontents themselves. The WEB browser 31 stores the transmitted part ofthe contents file in the data memory 34 (S108), and starts the viewer 32(S110). In the viewer 32, the contents file reading part 32 a reads anddeciphers the part of the contents file stored in the data memory 34 todecode the part of the file. With the use of the part of the contentsfile that has been decoded, the viewer body part 32 c displays themusical score corresponding to the part of the file by means of thedisplay 37 (S112). In this case, the musical score displayed on thedisplay 37 is only a part of the musical score corresponding to the partof the contents file. Moreover, it is not possible to print the musicalscore, and the displayed musical score is smaller in size or has arougher display resolution than usual in order to prevent the musicalscore from being hard-copied.

[0035] Here, in this embodiment, only a part of the requested contentsfile is supplied from the server 10 to the client terminal 30 in thisstate; however, the whole of the requested contents file may be suppliedfrom the server 10 to the client terminal 30. Nevertheless, in this casealso, the printing based on the supplied contents file is prohibited,and a part of the musical score corresponding to the part of the file isdisplayed in a small size. However, since the displayed musical score issmaller in size or has a rougher display resolution in order to preventthe musical score from being hard-copied as described above, the wholemusical score may be allowed to be displayed. Here, if the whole of thecontents file is supplied as described above, the transmittance of thewhole contents file in the later-mentioned procedure S166 will beunnecessary.

[0036] When the user gives an instruction of selection for purchasingthe displayed musical score with the use of the input key 36, theselection request is sent from the viewer 32 to the WEB browser 31(S114), and the WEB browser 31 transmits the selection request to theserver 10 (S116). In this case, the viewer 32 may generate a series ofmusic sounds corresponding to the contents file on the basis of thecontents data (musical score data) or other data contained in thecontents file with the use of a sound source circuit (not illustrated)incorporated in the client terminal 30, so as to facilitate theselection of the musical score by the user.

[0037] On the other hand, in the server 10, when the WEB server 11receives the selection request, a list of the musical scores (music)selected by the user is prepared (S118), and the prepared list istransmitted to the client terminal 30 (S120). In the client terminal 30,the WEB browser 31 receives the selection list, and displays thecontents of the selection list on the display 37 (S122). The selectionlist contains the contents identification data CID showing the contentsthemselves; however, what are displayed are the name of the music, thecomposer of the music, and others. At the same time, the display 37displays the waiting for an instruction on which is to be selected:addition of a new contents file, cancellation of the already selectedcontents file, or end of the operation of selecting the contents file.

[0038] When the user gives an instruction on which is to be selected:addition of a contents file, cancellation, or end of selection with theuse of the input key 36, the viewer 32 informs the WEB browser 31 of theinstruction (S124, S126). If the WEB browser 31 is informed of additionor cancellation, the WEB browser 31 informs the server 10 to that effect(S128). In the case of addition, the WEB browser 31 starts theabove-described request of the contents file (S100) again. This allowsthe contents files requested by the user to be successively added to theselection list according to the procedures of S100 to S122. In the caseof cancellation, the WEB server 11 deletes the cancelled contents filefrom the prepared selection list, and transmits the selection list againto the client terminal 30 (S120). Then, in the client terminal 30, theWEB browser 31 renews the selection list (S122).

[0039] On the other hand, if an instruction for the end of selection issent from the viewer 32 to the WEB browser 31 (S126), the WEB browser 31informs the server 10 of the end of selection (S130). In the server 10,the WEB server 11 prepares a purchase list containing a purchase fee aswell as the contents of the prepared selection list (S132), andtransmits the purchase list and the confirmation on the purchase to theclient terminal 30 (S134).

[0040] In the client terminal 30, the WEB browser 31 informs the viewer32 of the purchase list and the confirmation of purchase (S136), and theviewer 32 displays the purchase list and the confirmation of purchase onthe display 37 (S138). In this case, the display 37 displays the name ofthe music selected by the user, the composer of the music, the purchasefee, and others, and also displays an inquiry on the method of payment(for example, a credit card number CNO) as the confirmation of purchase.When the user requests for purchase and inputs the method of paymentwith the use of the input key 36, the viewer 32 informs the WEB browser31 of the request for purchase, the method of payment (credit cardnumber CNO), and others (S140), and the WEB browser 31 transmits therequest for purchase, the method of payment (credit card number CNO),and others to the server 10 (S142).

[0041] In the server 10, in response to the request for purchase, theWEB server 11 charges a fee on the user in accordance with the method ofpayment which has been transmitted (S144), and thereafter the chargedfee is collected from the user. After charging the fee, the WEB server11 prepares a receipt corresponding to the purchase list (S146), andtransmits the receipt file to the client terminal 10 (S148). Thisreceipt file contains the data on the music corresponding to thecontents (musical scores) purchased by the user, such as the name of themusic and the composer, fees of the music and the total sum of the feesfor purchase, as well as the contents identification data CIDcorresponding to the contents themselves.

[0042] In the client terminal 30, the WEB browser 31 informs the viewer32 of the receipt file (S150), and the viewer 32 stores the receipt filein the data memory 34 (S152), and the display 37 displays the name ofthe music of the contents (musical scores), the composer, and others ofthe purchased contents (musical scores), fees of the music, and thetotal sum of the fees for purchase in accordance with the receipt file,as well as the confirmation on the receipt of the receipt file (S154).

[0043] When the user confirms the receipt with the use of the input key36, the run time ID generating part 33 operates in response to theconfirmation operation with the input key 36 to generate a runtimeidentification data RID (random number of plural bits) which issynchronized with the timing of the confirmation operation. This runtimeidentification data RID is stored by the viewer 32 into the data memory34 in correspondence with the purchase file (S156). At the same time,the viewer 32 informs the WEB browser 31 of the confirmation of receiptand the runtime identification data RID (S158), and the WEB browser 31transmits the confirmation of receipt and the runtime identificationdata RID to the server 10 (S160).

[0044] In the server 10, the WEB server 11 stores the transmittedconfirmation of receipt and the runtime identification data RID into thedatabase 13 (S162). The WEB server 11 reads all the contents filesrelated to the designated contents (musical scores) out from thedatabase 13 on the basis of the receipt file (the same applies in thecase of the selection list and the purchase list) (S164), and transmitsthe whole contents files to the client terminal 30 (S166). In the clientterminal 30, the WEB browser 31 receives the whole contents files thathave been transmitted, stores the contents files into the data memory 34(S168), and transmits the completion of receiving to the server (S170).

[0045] In the server 10, in response to the completion of receiving, theWEB server 11 starts the key-issuing server 12 and informs thekey-issuing server 12 of the contents identification data CIDrespectively corresponding to all of the transmitted contents (musicalscores) and the runtime identification data RID received from the clientterminal 10 (S172). The key-issuing server 12 prepares a key filecontaining the contents identification data CID and the runtimeidentification data RID, and encodes the key file to pass the key fileto the WEB server 11 (S174). The WEB server 11 transmits the encoded keyfile to the client terminal 30 (S176). At this time, the key file isalso stored into the database 13.

[0046] In the client terminal 30, the WEB browser 31 stores thetransmitted key file into the data memory 34 (S178). This allows thedata memory 34 of the client terminal 30 to store all the contents filespurchased by the user and the key file representing the purchase, and tostore the runtime identification data RID formed by the procedure S156together with the contents identification data CID showing the contentsthemselves.

[0047] Next, the case of printing the contents (musical scores) will bedescribed. In this embodiment, with the viewer 32 started, the useroperates the input key 36 to allow the data memory 34 to read thecontents file and the key file out, and the contents (musical scores)are printed under a condition of the presence of an appropriate key file(S200 in FIG. 2).

[0048] This operation will be described with the use of the flowchartsshown in FIGS. 3 to 5. Referring to FIG. 3, the key input processingprogram in the viewer 32 is repeatedly executed from the time of beingstarted in the step 200 in FIG. 3 (S110 in FIG. 2) till the instructionfor the end of the processes of the steps 202 to 206 is given. In thestep 202, whether the input key 36 has been operated or not isdetermined, and if the key 36 is not operated, the process of the step202 continues to be executed. If the input key 36 is operated, thedetermination of “YES is given in the step 202, and whether theoperation of the input key 36 is an instruction for the end of theprocesses or not is determined in the step 204. If the operation of theinput key 36 is not an instruction for the end of the processes, thedetermination of “NO is given in the step 204, and the processcorresponding to the operated input key 36 is executed in the step 206.

[0049] In this case, only the processes related to the printing of thecontents (musical scores) related to the present invention will bedescribed. If an instruction for the process of opening the designatedfile is given by the input key 36, the file processing routine of FIG. 4is executed in the step 206. This file processing routine is started inthe step 220 of FIG. 4, and the designated file (in this case, eitherthe contents file or the key file) is read out from the data memory 34and the read-out file is deciphered to decode the file in the step 222.Next, whether the decoded file is a key file or not is determined in thestep 224.

[0050] If the decoded file is a key file, the determination of “YES” isgiven in the step 224, and whether the decoded key file is valid or notis determined in the step 226. In this determination, the contentsidentification data CID and the runtime identification data RIDcontained in the key file are respectively compared with the contentsidentification data CID contained in the receipt file stored in the datamemory 34 by the procedure S152 and the runtime identification data RIDstored in the data memory 34 by the procedure S156. If each of thecontents identification data CID and the runtime identification data RIDis coincident, the key file is determined to be valid.

[0051] If the key file is valid, the determination of “YES” is given inthe step 226, and the restriction on printing is released. Specifically,a printing restriction releasing flag representing the release of therestriction on printing is each added to one or more contentsidentification data CID (contents identification data CID correspondingto one or more contents files purchased by the user) contained in thedecoded key file. The contents identification data CID to which theprinting restriction releasing flag has been added is temporarily storedas a printing restriction releasing file. Here, the temporary storage ofthe printing restriction releasing file refers to storage in a RAM orthe like of the client terminal 30, and the printing restrictionreleasing file is erased at the time of the end of the operation of theviewer 32. Next, the key file is erased from the data memory 34 in thestep 230. This makes it impossible to read the key file out again.

[0052] On the other hand, if the file decoded by the process of the step222 is a contents file, the determination of “NO is given in the step224, and the contents file (musical score file) is displayed on thedisplay 37 in the step 232. In this case also, the musical scoredisplayed on the display 37 is sufficiently small in size and has arough display resolution in order to prevent the musical score frombeing hard-copied. In this case, however, the operation of the input key36 allows all the pages of the designated contents file (musical scoreof the designated music) to be displayed. After the process of the step230 or the step 232, the execution of the file processing routine istemporarily ended in the step 234.

[0053] If an instruction for printing the contents file (musical score)is given by the input key 36 in a state in which the contents file(musical score) is displayed on the display 37 as described above, theprinting processing routine of FIG. 5 is executed in the step 206 ofFIG. 3. This printing processing routine is started in the step 240 ofFIG. 5, and whether the restriction on the printing of the contents(musical scores) being displayed on the display 37 is released or not isdetermined in the step 242. In this determination, whether the contents(musical score) currently being displayed can be printed or not isdetermined by making reference to the printing restriction releasingfile. Namely, whether or not the printing restriction releasing flag hasbeen added to the contents identification data CID coincident with thecontents identification data CID corresponding to the contents (musicalscore) being displayed and stored in the printing restriction releasingfile, is determined.

[0054] If the restriction on the printing of the contents (musicalscore) being displayed is released, the determination of “YES” is givenin the step 242, and the confirmation of printing (for example, displayof “whether the printing is to be performed or not ) is carried out bythe display 37 in the step 244. In this case, it is convenient if thesize of printing paper, characters for printing, size of the musicalscore to be printed, pages to be printed, and others can be designated.If the user gives an instruction for printing with the use of the inputkey 36, the determination of “YES given in the step 244, and the printer38 is controlled in the step 246, whereby the contents (musical score)being displayed are printed.

[0055] Thus, a plurality of contents (musical scores) stored in the datamemory 34 can be successively printed by repeating the process ofdisplaying the contents (musical scores) on the display 37 and printingthe contents (musical scores) by the printing process as describedabove. Also, in the confirmation of the printing, if the user gives aninstruction to the effect of not printing with the use of the input key36, the determination of “NO” is given in the step 244, and theexecution of the printing processing routine is temporarily ended in thestep 254.

[0056] On the other hand, if the determination of “NO” is given in thedetermination on the release of the restriction on printing in the step242, i.e. if it is determined that the restriction on the printing ofthe contents (musical score) being displayed is not released, theprocedure is forwarded to the process of the step 248. In the step 248,the display 37 displays an inquiry to the user on whether the contents(musical score) being displayed is to be purchased or not, and aninstruction of the user is awaited in the step 250. If the user wishesto purchase the contents (musical score) with the use of the input key36, the determination of “YES is given in the step 250, and theprocedure of the purchasing process, i.e. the process of forwarding theprogram to the stage just before the procedure S114 of FIG. 2, isexecuted in the step 252. Further, if the user does not wish to purchasethe contents (musical score), the determination of “NO is given in thestep 250, and the execution of this printing processing routine istemporarily ended in the step 254.

[0057] Further, if the user gives an instruction for the end with theuse of the input key 36 in the key input processing program of FIG. 3,the determination of “YES” is given in the step 204, and the executionof this key input processing program is ended in the step 208. Here, theend of execution of the key input processing programs signifies the endof the operation of the viewer 32 as well, and the viewer 32 does notstart the operation unless it is started again.

[0058] As will be understood from the above description, according tothe above embodiment, the contents files representing the musical scoresare supplied from the server 10 side to the client terminal 30 side byinteraction between the client terminal 30 and the server 10 via thecommunication line 20, and the client terminal 30 can print the musicalscores represented by the supplied contents files, so that the user canobtain various musical scores with ease. In this case, the key file issent from the server 10 side to the client terminal 30 side only whenthe client terminal 30 expresses a wish of purchase, and the key filereleases the restriction on the printing of the contents (musicalscores), thereby preventing unlimited printing of the contents (musicalscores). Moreover, the user can confirm the part of the contents(musical scores) that the user wishes to print on the display 37, andcan view or listen to the part of the music corresponding to the musicalscores, thereby providing convenience for the user.

[0059] Further, in preparing the key file, the runtime identificationdata RID is sent from the client terminal 30 side to the server 10 sidein accordance with the timing of the wish of purchase by the user, andthe server 10 prepares a key file containing the runtime identificationdata RID and the contents identification data CID corresponding to thecontents file that the user wishes. This key file is sent to the clientterminal 30, and the client terminal 30 compares the key file with theruntime identification data RID that was stored when the runtimeidentification data RID was sent to the server 10. In accordance withthe result of the comparison, the restriction on the printing of thecontents (musical score) is released. In this case, in generating theruntime identification data RID, the runtime identification data RID isgenerated at random in accordance with each timing of expressing thewish of purchase by the user, so that an identical value is least likelyto be given as the runtime identification data RID, whereby the releaseof the restriction on the printing is carried out simply and accurately.

[0060] Here, in the above-described embodiment, as long as the viewer 32is in operation, the printing restriction releasing file once preparedis preserved in the RAM, so that the user can print the contents(musical scores) whose restriction on printing is released, as manytimes as the user wishes. Therefore, in this case, even if the userfails to print the contents (musical scores) once, the user can printthe contents (musical scores) again, thereby providing convenience forthe user. However, if the operation of the viewer 32 is ended, theprinting restriction releasing file is erased from the RAM, and also,since the key file is erased after the printing restriction releasingfile is prepared, it is not possible to print the musical scores.

[0061] Further, as long as the operation of the viewer 32 is continued,unlimited printing of the contents (musical scores) by the user ispermitted, so that the number of times for printing may be limited. Inthis case, in the printing process in the step 246 of FIG. 5, the numberof times for printing may be counted and stored for each of the printedcontents (musical scores), and the determination on the release of therestriction on printing may be carried out under such a condition thatthe counted number does not exceed a predetermined number of times foreach of the contents (musical scores) in addition to the condition suchthat the above-described printing restriction releasing flag is set.This limits the number of times for printing the contents (musicalscores) to be under a predetermined number each time the viewer 32 isstarted.

[0062] Further, in the case of limiting the number of times forprinting, the printing restriction releasing file and the counted numbermay be stored in the data memory 34 to allow them to be preserved alsowhen the operation of the viewer 32 is ended, instead of erasing theprinting restriction releasing file when the operation of the viewer 32is ended. This makes it possible to print the contents (musical scores)up to a predetermined number of time when the viewer 32 is started againafter the operation of the viewer 32 is once ended.

[0063] Further, the number of times for permitting the printing may beencoded and stored in the key file, and the number of times for allowingthe printing may be arbitrarily designated. For example, the number oftimes may be designated when the contents file is purchased, or thenumber of times may be determined in various ways in accordance with thetype of the contents.

[0064] Furthermore, instead of limiting the number of times for printingthe contents (musical scores), the restriction on the printing of thecontents (musical scores) may be released until a predetermined periodof time passes or until a predetermined time limit after the time pointwhen the user issues the request for purchase (the time when the runtimeidentification data RID is transmitted from the client terminal 30 tothe server 10). In this case, the predetermined time obtained by addinga predetermined period of time to the aforesaid time point or thepredetermined time after the aforesaid time point may be stored in theclient terminal 30, and the determination on the release of therestriction on printing may be carried out under a condition such thatthe current time is before the stored predetermined time point with theuse of a clock circuit (timer circuit) incorporated in the clientterminal 30 in addition to the condition such that the aforesaidprinting restriction releasing flag is set as described before in thestep 242 in FIG. 5.

[0065] In this case also, if the printing restriction releasing file andthe predetermined time point are stored in the RAM and erased when theoperation of the viewer 32 is ended, the repeated printing of thecontents (musical scores) is limited to the period of time when theviewer 32 is in operation. Further, if the printing restrictionreleasing file and the predetermined time point are stored in the datamemory 34 and preserved also at the time when the operation of theviewer 32 is ended, the printing of the contents (musical scores) can becarried out until the aforesaid time point in the case where the viewer32 is started again.

[0066] Further, these limitations to the predetermined number of times,the predetermined period of time, and the predetermined time limit maybe managed on the server 10 side. In this case, the printing restrictionreleasing file, the number of times for printing by the client terminal30, the predetermined period of time, the predetermined time limit, andothers may be stored in the database 13, and the printing of thecontents (musical scores) may be permitted under the aforesaid conditionin accordance with the request sent from the client terminal 30 side tothe server 10 side. In this case, the server 10 may each time transmitthe data that permits the printing of the contents (musical scores) tothe client terminal 30 or transmit the key file to the client terminal30.

[0067] Further, in the above embodiment, in response to the request ofthe client terminal 30, the server 10 transmits the requested contentsfiles one by one via the communication line 20 and, in response to thetransmittance of the runtime identification data RID from the clientterminal 30, transmits the key file to the client terminal 30 via thecommunication line 20. However, with regard to the contents files, allof the contents files or a large number of contents files stored in thedatabase 13 may be transmitted to the client terminal 30 via thecommunication line 20, and the client terminal 30 side may store theaforesaid all of or large number of contents files in the data memory34. Further, a recording medium such as a CD or an MD that contains alarge number of contents files may be distributed to the user by amethod such as postal service, home delivery service, or the like. Inthis case, the user may start the viewer 32 to read the contents filesstored in the data memory 34 or in the recording medium such as a CD oran MD to display them on the display 37, and transmit the request forselection of the desired contents files to the server 10. In otherwords, the user may purchase the contents files according to theprocedure after S114 of FIG. 2.

[0068] Further, in the above embodiment, in response to the request ofthe client terminal 30, the server 10 transmits the key file to theclient terminal 30 only once; however, the server 10 may reissue the keyfile in accordance with a request given by the client terminal 30 withina predetermined number of times or within a predetermined period oftime. In this case, in the server 10, the key-issuing server 12 maycount the number of times for the transmittance of the key file, ormeasure the period of time since the first issuance of the key file and,only in the case where the counted number is within a predeterminedvalue or where the measured period of time is within a predeterminedperiod of time, the server 10 may reissue the key file in response tothe request given by the client terminal 30. This makes it possible forthe client terminal 30 to release the restriction on the utilization ofthe contents files one purchased even in the case where the clientterminal 30 has lost the key file before using the key file by adisorder or an operation error of the client terminal 30, therebyproviding convenience for the user.

[0069] Further, in the above embodiment, after the user selects pluralcontents files one by one, the user purchases the plural contentssimultaneously. However, instead of this, each time the user selects thecontents file, the user may be allowed to purchase the contents file. Inthis case, for each contents file, one key file is supplied from theserver 10 to the client terminal 30.

[0070] Further, in the above embodiment, after the user gives aninstruction for the purchase of the contents files with the use of theinput key 36, the server 10 executes the process of charging a fee andthe process of transmitting the receipt file, and thereafter, theconfirmation on the receiving of the receipt file is carried out, and,at that time, the runtime identification data RID generated in theruntime ID generating part 33 is transmitted to the server 10 (S140 toS160). However, for simplifying this, the runtime identification dataRID corresponding to the timing of the request for purchase may betransmitted to the server 10 simultaneously with giving the instructionto purchase the contents files without waiting for the receipt file tobe received. In this case, the receipt file, all the contents files, thekey files, and others are transmitted simultaneously from the server 10to the client terminal 30 after the user gives an instruction ofpurchase.

[0071] Further, in the above embodiment, the client terminal 30 performsall the communications to the server 10 for purchasing the contentsfiles with the use of a personal computer. However, a part of thecommunications with the server 10 may be carried out by differentcommunication means, for example, by telephone, portable telephone,postal service, home delivery service, or the like. For example, whenthe user gives a request of purchase to the viewer 32 on the clientterminal 30 side (S140 in FIG. 2), the runtime identification data RIDgenerated in the runtime ID generating part 33 is allowed to bedisplayed on the display 37. The data corresponding to the separatelydisplayed contents (which may be a contents identification data CID) andthe displayed data RID are sent to the server 10 side by the differentcommunication means described above. The server 10 side takes both ofthese sent data into the key-issuing server 11 by a manual operation orthe like, forms a key file in the same manner as in the aboveembodiment, and sends the formed key file to the user by the differentcommunication means. The user takes the key file into the viewer 32 ofthe client terminal 30 with the use of the input key 36 or the like.This makes it possible for the client terminal 30 to print the contents(musical scores). This method is especially effective if all of or alarge number of the contents files stored in the database 13 are alreadytransmitted to the client terminal 30 side in advance by thecommunication line 20, or by a CD or an MD.

[0072] Further, in the above embodiment, the communication between theserver 10 and the client terminal 30 is carried out via thecommunication line (network) 20 such as the internet, a public telephoneline, an exclusive-use line, or a LAN; however, the communication line20 is not limited to a wired line, so that one may utilize a wirelessline such as a satellite communication line, a portable wirelesstelephone line, or a BlueTooth.

[0073] Further, in the above embodiment, an example has been describedin which a personal computer (a general-purpose computer) is used as theclient terminal 30 which is a terminal device. However, as the terminaldevice, various apparatus that can communicate information with otherapparatus, such as a portable personal information terminal (PDA), aportable telephone, a game apparatus for home use (including a portablegame apparatus), a copying machine, a facsimile device, or an electronicmusical instrument can be utilized instead of the general-purposecomputer as long as the apparatus includes a microprocessor functioningpart such as a CPU, an interface part or the like for receiving datasuch as a contents data and a key file via the aforesaid broad-sensecommunication line 20, a storage part for storing a program thatoperates in the above-mentioned manner and the received data, autilization apparatus for utilizing the contents (a printer in the aboveembodiment), a driver for driving the utilization apparatus, and aninterface part that enables wired or wireless connection with theapparatus.

[0074] Further, in the above embodiment, an example has been describedin which the present invention is applied to a distributing system forsupplying a musical score from the server 10 to the client terminal 30as the contents; however, the present invention can be applied also to acase for distributing other contents such as sentences, various figures(maps, paintings, photographs, and others), music, or programs. In thecase of sentences or various figures, restriction on printing, displayof clear images, or the like may be released with the use of a key fileformed as in the above embodiment. In the case of music, data such asMIDI data may be adopted as the data, and restriction on the range oflistening to the music may be released with the use of the key file. Forexample, without the key file, data consisting only of some measures orparts forming a part of the music may be reproduced and, with the keyfile obtained, all the data may be reproduced. In the case of a program,restriction on the execution of the program may be released with the useof the key file. In this case, without the key file, only a generalsummary of the program may be introduced and, with the key fileobtained, the program may be made executable.

[0075] Lastly, this invention may be practiced or embodied in stillother ways without departing from the spirit or essential characterthereof as described heretofore. Therefore the preferred embodimentdescribed herein is illustrative and not restrictive, the scope of theinvention being indicated by the appended claims and all variationswhich come within the meaning of the claims are intended to be embracedtherein.

What is claimed is:
 1. A contents-distributing system comprising aserver and a client terminal that are communicable with each other, saidserver including: a database for storing a plurality of contents;contents-transmitting means for transmitting the contents in saiddatabase to said client terminal in accordance with a request from saidclient terminal; and key file transmitting means for transmitting a keyfile to said client terminal in accordance with a request from saidclient terminal, said key file releasing restriction on utilization ofone or more contents transmitted to said client terminal, and saidclient terminal including: contents-requesting means for sending arequest of the contents stored in said database to said server; key filerequesting means for sending a request of said key file to said server;a data memory for storing the contents and the key file transmitted fromsaid server; utilization restricting means for restricting theutilization of the contents stored in said data memory; and utilizationrestriction releasing means for releasing the restriction on theutilization of the contents by said utilization restricting means undera predetermined condition in accordance with the key file stored in saiddata memory.
 2. The contents-distributing system according to claim 1 ,wherein the utilization restricting means included in said clientterminal introduces said contents to a user in said client terminal byutilization of only a part of said contents.
 3. Thecontents-distributing system according to claim 1 , wherein theutilization restriction releasing means included in said client terminalreleases the restriction on the utilization of the contents underconstraint of the number of times for the utilization or underconstraint of time.
 4. The contents-distributing system according toclaim 3 , wherein the key file transmitting means included in saidserver allows the key file to be reissued for a predetermined number oftimes or within a predetermined period of time after the key file isinitially transmitted, in accordance with the request of the key filefrom said client terminal.
 5. The contents-distributing system accordingto claim 1 , wherein the utilization restriction releasing meansincluded in said client terminal erases said key file after releasingthe restriction on the utilization of said contents.
 6. Thecontents-distributing system according to claim 5 , wherein the key filetransmitting means included in said server allows the key file to bereissued for a predetermined number of times or within a predeterminedperiod of time after the key file is initially transmitted, inaccordance with the request of the key file from said client terminal.7. The contents-distributing system according to claim 1 , wherein saidclient terminal further includes identification data generating meansfor generating and storing an identification data specific to a timingof the request of said key file when said client terminal sends therequest of said key file to said server, and for transmitting theidentification data to said server together with the request of said keyfile, said key file transmitting means included in said server isconfigured to transmit the key file containing said identification data,and said utilization restriction releasing means included in said clientterminal is configured to release the restriction on the utilization ofsaid contents by comparison between the identification data stored insaid client terminal and the identification data contained in saidtransmitted key file.
 8. The contents-distributing system according toclaim 7 , wherein the identification data generating means included insaid client terminal is configured to form a value which changes atrandom in accordance with passage of time and which is synchronized withthe timing of the request of said key file.
 9. The contents-distributingsystem according to claim 1 , wherein said contents are musical scores,and said restriction on the utilization of said contents prohibitsprinting of the contents.
 10. The contents-distributing system accordingto claim 1 , wherein said server further includes fee-charging means forcharging a fee to a user in said client terminal when the request ofsaid key file is sent from said client terminal.
 11. Acontents-distributing system comprising a server and a client terminalthat are communicable with each other, said client terminal including:contents-storing means for storing a plurality of contents; key filerequesting means for sending a request of a key file to said server,said key file releasing restriction on utilization of one or morecontents among said plurality of contents; key file storing means forstoring the key file transmitted from said server; utilizationrestricting means for restricting the utilization of the contents storedin said contents-storing means; and utilization restriction releasingmeans for releasing the restriction on the utilization of the contentsby said utilization restricting means under a predetermined condition inaccordance with the key file stored in said key file storing means, andsaid server including: key file transmitting means for transmitting saidkey file to said client terminal in accordance with a request from saidclient terminal.
 12. The contents-distributing system according to claim11 , wherein the utilization restricting means included in said clientterminal introduces said contents to a user in said client terminal byutilization of only a part of said contents.
 13. Thecontents-distributing system according claim 11 , wherein theutilization restriction releasing means included in said client terminalreleases the restriction on the utilization of the contents underconstraint of the number of times for the utilization or underconstraint of time.
 14. The contents-distributing system according toclaim 13 , wherein the key file transmitting means included in saidserver allows the key file to be reissued for a predetermined number oftimes or within a predetermined period of time after the key file isinitially transmitted, in accordance with the request of the key filefrom said client terminal.
 15. The contents-distributing systemaccording to claim 11 , wherein the utilization restriction releasingmeans included in said client terminal erases said key file afterreleasing the restriction on the utilization of said contents.
 16. Thecontents-distributing system according to claim 15 , wherein the keyfile transmitting means included in said server allows the key file tobe reissued for a predetermined number of times or within apredetermined period of time after the key file is initiallytransmitted, in accordance with the request of the key file from saidclient terminal.
 17. The contents-distributing system according to claim11 , wherein said client terminal further includes identification datagenerating means for generating and storing an identification dataspecific to a timing of the request of said key file when said clientterminal sends the request of said key file to said server, and fortransmitting the identification data to said server together with therequest of said key file, said key file transmitting means included insaid server is configured to transmit the key file containing saididentification data, and said utilization restriction releasing meansincluded in said client terminal is configured to release therestriction on the utilization of said contents by comparison betweenthe identification data stored in said client terminal and theidentification data contained in said transmitted key file.
 18. Thecontents-distributing system according to claim 17 , wherein theidentification data generating means included in said client terminal isconfigured to form a value which changes at random in accordance withpassage of time and which is synchronized with the timing of the requestof said key file.
 19. The contents-distributing system according toclaim 11 , wherein said contents are musical scores, and saidrestriction on the utilization of said contents prohibits printing ofthe contents.
 20. The contents-distributing system according to claim 11, wherein said server further includes fee-charging means for charging afee to a user in said client terminal when the request of said key fileis sent from said client terminal.
 21. A contents-distributing methodusing a server that stores a plurality of contents in a database and aclient terminal that is communicable with said server, wherein one ormore contents among said plurality of contents stored in said databaseare supplied from said server to said client terminal in accordance witha request from said client terminal to said server; a key file forreleasing restriction on utilization of said one or more contents issupplied from said server to said client terminal in accordance with arequest from said client terminal to said server, and the restriction onthe utilization of the contents supplied from said server to said clientterminal is released in accordance with the key file supplied from saidserver to said client terminal.
 22. The contents-distributing methodaccording to claim 21 , wherein an identification data specific to atiming of the request of said key file is generated and stored in saidclient terminal when said client terminal sends the request of said keyfile to said server, and said identification data is supplied from saidclient terminal to said server together with the request of said keyfile, said identification data is allowed to be contained in said keyfile when the key file is supplied from said server to said clientterminal; and the restriction on the utilization of said contents isreleased by comparison between said stored identification data and theidentification data contained in said supplied key file when said clientterminal releases the restriction on the utilization of the contents.23. The contents-distributing method according to claim 21 , wherein afee is charged to a user in said client terminal when the request ofsaid key file is sent from said client terminal to said server.
 24. Acontents-distributing method using a client terminal that stores aplurality of contents and a server that is communicable with said clientterminal, wherein a key file for releasing restriction on utilization ofone or more contents among said plurality of contents stored in saidclient terminal is supplied from said server to said client terminal inaccordance with a request from said client terminal to said server, andthe restriction on the utilization of said one or more contents isreleased in said client terminal in accordance with the key filesupplied from said server to said client terminal.
 25. Thecontents-distributing method according to claim 24 , wherein anidentification data specific to a timing of the request of said key fileis generated and stored in said client terminal when said clientterminal sends the request of said key file to said server, and saididentification data is supplied from said client terminal to said servertogether with the request of said key file, said identification data isallowed to be contained in said key file when the key file is suppliedfrom said server to said client terminal; and the restriction on theutilization of said contents is released by comparison between saidstored identification data and the identification data contained in saidsupplied key file when said client terminal releases the restriction onthe utilization of the contents.
 26. The contents-distributing methodaccording to claim 24 , wherein a fee is charged to a user in saidclient terminal when the request of said key file is sent from saidclient terminal to said server.
 27. A server that is communicable with aclient terminal, said server comprising: a database for storing aplurality of contents; contents-transmitting means for transmitting thecontents in said database to said client terminal in accordance with arequest from said client terminal; and key file transmitting means fortransmitting a key file to said client terminal in accordance with arequest from said client terminal, said key file releasing restrictionon utilization of one or more contents among said plurality of storedcontents.
 28. The server according to claim 27 , wherein said serverfurther includes fee-charging means for charging a fee to a user in saidclient terminal when the request of said key file is sent from saidclient terminal.
 29. A server that is communicable with a clientterminal having contents-storing means for storing a plurality ofcontents, said server comprising: key file preparing means for preparinga key file in accordance with a request from said client terminal, saidkey file releasing restriction on utilization of one or more contentsamong said plurality of contents; and key file transmitting means fortransmitting said prepared key file to said client terminal.
 30. Theserver according to claim 29 , wherein said server further includesfee-charging means for charging a fee to a user in said client terminalwhen the request of said key file is sent from said client terminal. 31.A computer-readable recording medium containing a program applied to aserver which is communicable with a client terminal and which stores aplurality of contents in a database, said program including: acontents-transmitting process for transmitting one or more contentsamong said plurality of contents stored in said database to said clientterminal in accordance with a request from said client terminal; and akey file transmitting process for transmitting a key file to said clientterminal in accordance with a request from said client terminal, saidkey file releasing restriction on utilization of said one or morecontents.
 32. The computer-readable recording medium according to claim31 , wherein said program further includes a fee-charging process forcharging a fee to a user in said client terminal when the request ofsaid key file is sent from said client terminal.
 33. A computer-readablerecording medium containing a program applied to a server that iscommunicable with a client terminal that stores a plurality of contents,said program including a key file transmitting process for transmittinga key file to said client terminal in accordance with a request fromsaid client terminal, said key file releasing restriction on utilizationof one or more contents among said plurality of contents.
 34. Thecomputer-readable recording medium according to claim 33 , wherein saidprogram further includes a fee-charging process for charging a fee to auser in said client terminal when the request of said key file is sentfrom said client terminal.
 35. A client terminal that is communicablewith a server that stores a plurality of contents, said client terminalcomprising: contents-obtaining means for sending a request of thecontents to said server and for obtaining the requested contents fromsaid server; key file obtaining means for sending a request of a keyfile to said server, said key file releasing restriction on utilizationof said obtained contents, and for obtaining said requested key filefrom said server; utilization restricting means for restricting theutilization of said obtained contents; and utilization restrictionreleasing means for releasing the restriction on the utilization of thecontents by said utilization restricting means in accordance with theobtained key file.
 36. The client terminal according to claim 35 ,wherein said client terminal further includes identification datagenerating means for generating and storing an identification dataspecific to a timing of the request of said key file when said clientterminal sends the request of said key file to said server, and fortransmitting the identification data to said server together with therequest of said key file, the key file obtained by said key fileobtaining means corresponds to said identification data, and saidutilization restriction releasing means is configured to release therestriction on the utilization of said contents by comparison betweenthe identification data stored in said client terminal and theidentification data contained in said transmitted key file.
 37. A clientterminal that is communicable with a server, said client terminalcomprising: contents-storing means for storing a plurality of contents;key file obtaining means for sending a request of a key file to saidserver, said key file releasing restriction on utilization of one ormore contents among said plurality of stored contents, and for obtainingsaid requested key file from said server; utilization restricting meansfor restricting the utilization of said stored contents; and utilizationrestriction releasing means for releasing the restriction on theutilization of the contents by said utilization restricting means inaccordance with the obtained key file.
 38. The client terminal accordingto claim 37 , wherein said client terminal further includesidentification data generating means for generating and storing anidentification data specific to a timing of the request of said key filewhen said client terminal sends the request of said key file to saidserver, and for transmitting the identification data to said servertogether with the request of said key file, the key file obtained bysaid key file obtaining means corresponds to said identification data,and said utilization restriction releasing means is configured torelease the restriction on the utilization of said contents bycomparison between the identification data stored in said clientterminal and the identification data contained in said transmitted keyfile.
 39. A computer-readable recording medium containing a programapplied to a client terminal that is communicable with a server thatstores a plurality of contents, said program including: acontents-obtaining process for sending a request of one or more contentsamong said plurality of stored contents to said server and for obtainingthe requested contents from said server; a key file obtaining processfor sending a request of a key file to said server, said key filereleasing restriction on utilization of said obtained contents, and forobtaining said requested key file from said server; a utilizationrestricting process for restricting the utilization of said obtainedcontents; and a utilization restriction releasing process for releasingthe restriction on the utilization of the contents by said utilizationrestricting process in accordance with the obtained key file.
 40. Thecomputer-readable recording medium according to claim 39 , wherein saidprogram further includes an identification data transmitting process forgenerating and storing an identification data specific to a timing ofthe request of said key file when said client terminal sends the requestof said key file to said server, and for transmitting the identificationdata to said server together with the request of said key file, the keyfile obtained by said key file obtaining process corresponds to saididentification data, and said utilization restriction releasing processis configured to release the restriction on the utilization of saidcontents by comparison between the identification data stored in saidclient terminal and the identification data contained in saidtransmitted key file.
 41. A computer-readable recording mediumcontaining a program applied to a client terminal which is communicablewith a server and which stores a plurality of contents, said programincluding: a key file obtaining process for sending a request of a keyfile to said server, said key file releasing restriction on utilizationof one or more contents among said plurality of stored contents, and forobtaining said requested key file from said server; a utilizationrestricting process for restricting the utilization of said storedcontents; and a utilization restriction releasing process for releasingthe restriction on the utilization of the contents by said utilizationrestricting process in accordance with the obtained key file.
 42. Thecomputer-readable recording medium according to claim 41 , wherein saidprogram further includes an identification data transmitting process forgenerating and storing an identification data specific to a timing ofthe request of said key file when said client terminal sends the requestof said key file to said server, and for transmitting the identificationdata to said server together with the request of said key file, the keyfile obtained by said key file obtaining process corresponds to saididentification data, and said utilization restriction releasing processis configured to release the restriction on the utilization of saidcontents by comparison between the identification data stored in saidclient terminal and the identification data contained in saidtransmitted key file.